Electronic control systems are utilized for operating drive motors for vehicles. With the aid of the electronic control systems, the adjustable power parameter(s) of the drive motor is (are) determined in dependence upon input quantities. Some of these electronic control systems operate on the basis of a torque structure, that is, torque values are pregiven as desired values for the control system by the driver and, if required, from other control systems such as road speed controllers, electronic stability programs, transmission controls, et cetera. These torque values are converted by the control systems while considering additional operating variables into adjusting quantities for the power parameter(s) of the drive motor. An example for such a torque structure is known from DE 42 39 711 A1 (U.S. Pat. No. 5,558,178).
As described by way of example in this state of the art, the external interventions operate to reduce torque. In the extreme case, such an external intervention can reduce the rpm of the drive motor so much that the drive motor stalls. An example for a solution which prevents such a stalling is set forth in DE 197 39 567 A1. There, the output signal of the idle control is directly superposed on the driver command torque pregiven as an indicated engine torque. The driver command torque additionally contains the lost torques from internal motor friction and required torques of the ancillary equipment. The driver command torque can, in this way, not be less than zero. If a torque reduction occurs because of other control systems (for example, transmission, stability control), then a stalling of the engine is avoided because this external intervention in the subsequent coupling of the desired torques (torque coordination) can no longer intervene because of the high driver command torque. In lieu of this external intervention, the driver command torque becomes effective which is increased by lost torque and idle controller component. This solution is adapted specifically to the conditions in the control of a spark-ignition engine and can neither be applied in a simple manner to other drive types nor to other torque structures, for example, to structures which form the driver command at the wheel torque level.